4DRZ

iTrader: (7)

I did a track day at Road America and my ABS went out. It turns out the rear ABS sensors are plastic and mount to the rear differential. For some reason they got hot and melted and as a result they are not covered under warranty.

I cannot find any pictures showing that the stock exhaust has any type of heat shield at the back of the rear differential. The reason I ask ss the service advisor made it sound like it was partially due to my Stillen exhaust.

Does anyone know if the stock exhaust has heat shields by the back of the rear differential or can you take a quick look? Anyone else have this problem and know a solution?

Thanks!

Rochester

iTrader: (9)

I can't help you, except to point out that most Nissan dealerships will install Stillen exhausts as a dealer-installed option. (That was redundant, LOL.) In other words, blaming Stillen sure feels like a cop-out.

This was my stock exhaust. I don't recall removing anything other than what you see here.

4DRZ

iTrader: (7)

I agree and thanks for the pic. I was looking at diagrams last night in parts catalogs and it did not look like I was missing any heat shields. This confirms it.

It seems strange to me that Infiniti would mount something as important as ABS sensors made out of plastic directly to the rear diff if it gets hot. If I had not reacted as quickly as I did I could have easily slid off the track and hit a wall. (Still not quick enough, as I had to order 2 new front tires yesterday)

I was hitting speeds around 135 in the straights at Road America, but the car should be able to go faster. I can understand if I was drifting the car or doing donuts and the wheels were spinning a lot and heating up the diff, but it seems odd that it would get that hot from lapping.

It sounds pretty doubtful that they are going to warranty it. I guess if I do more track days I can always get a diff cover with cooling plates to see if that helps.

dkmura

There's something else going on with your car if you are melting the rear wheel ABS sensors. As an SCCA racer, I've raced at Road America and other tracks around the US and NEVER had a rear sensor melt. Infiniti uses a heat resistant plastic that has been proven durable over many years and models.

Rochester

iTrader: (9)

I was thinking that, too, but had no way of knowing. It seems inconceivable that the sensor would be in a plastic housing that couldn't withstand extreme heat.

OP, rather than chasing down this mythical and magical heat shield, can you cover the sensors somehow, with something like header-wrap?

On a side note... OMG. You scare me, man. All my years of irresponsible barnstorming on public roads are nothing compared to what you're doing on a road track with a DD. /respect

4DRZ

iTrader: (7)

You raced at RA in a G37S sedan? I have driven at RA in tons of other cars and never had this issue before, but this may be the 1st car that has this stupid design.

The top part of the sensor literally plugs into a hole on the top of the rear diff and sits on top of the back of the diff so unfortunately, there is no way to insulate it more from the differential.


Do you guys think the fluid in the rear diff could be toast and is causing more friction and thus more heat, causing the problem? I think you guys might be onto something as it smelled like something was burning just from driving back on normal roads and I do not remember anything smelling like that from the other track days. The car only has about 24k miles on it.

Rochester

iTrader: (9)

The service recommendation is 30K miles for differential gear oil. I'm at 32K on the original diff fluid, but I'm also a garage queen, and will be swapping rear gears next spring (knock on wood). If you road-track your car, and I suspect drive it pretty hard on the street (because racecar), then...



And now I feel awkward even being in the conversation.

SonicVQ

The issue is the unusual ABS sensor mounting on the diff (and not at the wheel/hub) and the high diff temps.

During the summer just putting around town for about 20 minutes on a 30 deg C day, my diff case measured just over 70 deg C. Actual fluid temp would be a little higher. This was with 1 week old 80W90 GL-5 from the dealer.

I was very surprised how how the diff got and I can imagine how it would get MUCH hotter when at the track.

Thoughts on the exhaust melting it:
I don't think the exhaust could put much heat into the ABS sensor as there is a LOT of air moving under the car.

Maybe try the higher capacity finned diff cover from Z1?

4DRZ

iTrader: (7)

No I don't drive very hard on the street. When you drive fast on the track you don't need to drive like a jackass on the street. No need to feel awkward. Thanks for the pic.

I think you are right. I just talked to Stillen about this, and they of course know nothing or have any suggestions. Then I called Z1 and they said they have seen other things melt in the diff, but I was the 1st to melt the ABS sensors. (I asked, but I do not get a prize for being the 1st)

For the time being I ordered some better redline fluid for the rear diff. If I go back to Road America or do some more track days I will switch to the Motul fluid and get their rear diff cover with the cooling fins.

More good news, the cost of the sensors was for both instead of just one so it is like they are 1/2 price. Already got the two new front tires on this morning so it no longer sounds like I am driving a tractor.

SonicVQ

Sounds like a fine plan. Please keep posting updates, I enjoy them.

4DRZ

iTrader: (7)

Good to hear. Thanks for posting up the temps of your diff. I have a infrared thermometer that I was going to check tonight and ask here for temps since I have no base line. Where are you from? I had to convert to degrees Fahrenheit

SonicVQ

Toronto. Normally I convert it to Fahrenheit, but I am on a one man mission to get the USA to join the rest of the world and enjoy the metric system.

(not really, just forgot to convert!)

4DRZ

iTrader: (7)

Oh Toronto, cool city! I drove at Mosport a few years ago. Fun track. I am with you on the metric system. Much easier to use my metric wrenches than the "standard" ones.